An electrical transformer based on helical electrodes applied to a plasma is described hereinafter. In previously disclosed devices (see U.S. patent application Ser. No. 14/648,014 by Nebel, and Ser. No. 15/336,508 by Finn et al.) a DC input voltage is applied to the helical electrodes and an output is taken from endcap electrodes at opposite the ends of the device. The presently disclosed apparatus also contains a radial magnetic field embedded in the helical electrodes and the secondary current is taken from solid or split (slotted) electrodes at the ends of the device. The system of the present disclosure also indicates methods for changing the output voltage and current relative to the input values. Thus, the present apparatus can function as either a stepup or a stepdown transformer. The system of the present disclosure can also be operated in reverse, with input voltage and current applied at the endcap electrodes and output voltage and current taken from the helical electrodes, thereby converting a stepup transformer to a stepdown transformer, and vice-versa. Although conventional methods can provide high voltage DC (HVDC) for long distance transmission, such methods are complex and costly. These and other shortcomings are addressed by the invention of the present disclosure.